1. Field
The presently disclosed subject matter relates to Transistor Outlined Can-typed (To-Can-typed) semiconductor light-emitting devices, and more particularly to To-Can-typed semiconductor light-emitting devices including a favorable radiating structure, which can efficiently radiate heat generated from a semiconductor light source, and also can enable principal parts of the devices not to require a high processing accuracy.
2. Description of the Related Art
Recently, various Transistor Outlined Can-typed (To-Can-typed) semiconductor light-emitting devices have been developed to meet a market need of small semiconductor light-emitting devices at low cost. To-Can-typed semiconductor light-emitting devices are, for example, disclosed in patent document No. 1 (Japanese Patent Application Laid Open JP2011-100785). FIG. 8 is an enlarged perspective view showing a conventional To-Can-typed semiconductor light-emitting device, which is disclosed in patent document No. 1.
The conventional semiconductor light-emitting deice 50 includes: a metallic cap 51 having a light-emitting window 51a; a metallic base 52 having through holes mounting the metallic cap 51 thereon; terminal pins 53 being hermetically sealed in a respective one of the through holes of the metallic base 52, respectively; a semiconductor light-emitting chip 55 having electrodes such as a light-emitting diode chip, a laser diode and the like being mounted on the metallic base 52, and each of the electrodes being electrically connected to a respective one of the terminal pin 53 via a respect one of bonding wires 54 so that the semiconductor light-emitting chip 55 can emit light when the electrodes of the chip 55 receive a power supply via the terminal pins 53; and wherein the metallic cap 51 is attached to the metallic base 52 so that the semiconductor light-emitting chip 55 can be airproofed between the metallic cap 51 and the metallic base 52.
Thereby, the conventional semiconductor light-emitting deice 50 enables the semiconductor light-emitting chip 55 to avoid a failure resulting from moisture absorption and a contamination of outer air, and may emit light emitted from the semiconductor light-emitting chip 55 from the light-emitting window 51a in a direction toward an emission thereof.
When the conventional semiconductor light-emitting deice 50 is used as a light source for a projector and the like, which needs a large amount of light to clearly project image data and the like, the semiconductor light-emitting device 50 may be subject to high temperature. Accordingly, to use the semiconductor light-emitting device 50 as a light source for the projector and the like, a heat sink may be required to radiate heat generated from the semiconductor light-emitting chip 55. However, when the To-Can typed semiconductor light-emitting device 50 is attached to a heat sink, because the metallic cap 51 may be made from a thin metallic plate in a manufacturing method such as a press working in general, it may be difficult for the metallic cap 51 to employ as a favorable heat-conducting path for the heat sink.
In addition, it may also be difficult for the metallic base 52 to employ as a favorable heat-conducting path for the heat sink using a side surface of the metallic base 52, because the metallic base 52 may require a space around the side surface thereof to adjust an optical axis of the device 50 in a direction toward the emission of the device 50. Moreover, when a bottom surface of the metallic base 52 is used as a dominant heat-conducting path for the heat sink, because the terminal pins 53 extend in an opposite direction of the metallic cap 51 from the bottom surface of the metallic base 52, the bottom surface of the metallic base 52 may also be difficult to use as the dominant heat-conducting path for the heat sink.
Hence, a conventional To-Can typed semiconductor light-emitting device including a heat sink is disclosed in patent document No. 2 (Japanese Patent Application Laid Open JP2012-9760). FIG. 9 is an enlarged cross-sectional view showing the conventional To-Can-typed semiconductor light-emitting device including a heat sink, which is disclosed in patent document No. 2.
The conventional semiconductor light-emitting deice 60 having a heat sink 66 includes: a metallic cap 61 having a light-emitting window; a metallic base 62 having an top surface 62a, a bottom surface 62b and through holes mounting the metallic cap 61 on the top surface 62a thereof, and the through holes passing through the metallic base 62; terminal pins 63 being hermetically sealed in the metallic base 62 via a respective of the through holes, respectively, so that a semiconductor light-emitting chip can emit light from the light-emitting window of the metallic cap 61 when the terminal pins 63 receive a power supply, and wherein the metallic cap 61 is attached to the metallic base 62 so that the semiconductor light-emitting chip can be airproofed between the metallic cap 61 and the metallic base 62.
In addition, the conventional semiconductor light-emitting deice 60 also includes: the heat sink 66, which is composed of a base plate 66a having a bottom surface 66b and a top surface 66c and a radiating fin 66d attached to the bottom surface 66b of the base plate 66a, the top surface 66c contacting with the bottom surface 62b of the metallic base 62; a holder 64 having an outer bottom surface 64a and an inner bottom surface 64b formed in an L-shaped structure in a cross-sectional view, and attaching the metallic base 62 to the heat sink 66 along with the metallic cap 61 between the inner bottom surface 64b and the top surface 66c of the base plate 66a; and a thermal conductive elastic member 65 being located between a side surface of the metallic base 62 and an inner side surface of the holder 64, which is located between the outer bottom surface 64a and the inner bottom surface 64b of the holder 64 that is formed in the L-shaped structure.
In the conventional semiconductor light-emitting device 60, heat generated from the semiconductor light-emitting chip mounted in the metallic cap 61 sealed by the metallic base 62 may transmit through a first thermal conductive path P1 from the bottom surface 62b of the metallic base 62 toward the top surface 66c of the base plate 66a, through a second thermal conductive path P2 from the top surface 62a of the metallic base 62 toward the top surface 66c of the base plate 66a via the inner bottom surface 64b and the outer bottom surface 64a of the holder 64, and through a third thermal conductive path P3 from the side surface of the metallic base 62 toward the top surface 66c of the base plate 66a of the heat sink 66 via the thermal conductive elastic member 65 and the outer bottom surface 64a of the holder 65.
However, the conventional semiconductor light-emitting device 60 may require each shape of the metallic base 62, the holder 65 and the base plate 66a of the heat sink 66, which may relatively become large, to be formed in a substantially uniformed shape. Specifically, the bottom surface 62b of the metallic base 62 should correspond to a substantially same level as the outer bottom surface 64a of the holder 64, the top surface 62a of the metallic base 62 should correspond to a substantially same level as the inner bottom surface 64b of the holder 64, and also the top surface 66b of the base plate 66a of the heat sink 66 should correspond to a substantially same level as the outer bottom surface 64a of the holder 64.
Therefore, a structure of the conventional semiconductor light-emitting device 60 may not allow each shape of the metallic base 62, the holder 65 and the base plate 66a of the heat sink 66 to even include a small tolerance. The conventional structure must require a high processing accuracy with reference to each of the metallic base 62, the holder 65 and the base plate 66a of the heat sink 66, and therefore should be always subject to a use of manufacturing machines at high cost, a long manufacturing time, a high manufacturing cost, etc.
In addition, when the conventional semiconductor light-emitting device 60 is used as a light source for the projector such that projects image data on a screen provided in a room, a quantity of misalignment of the optical axis of the device 60 may be allowed because a distance between the projector and the screen may be relatively short, and also may be generally constant. However, when the conventional structure of the To-Can typed semiconductor light-emitting device 60 is used as a light source for a vehicle headlight, which is required to form a favorable light distribution pattern with a wide range under varied surrounds, the quantity of misalignment of the optical axis of the device 60 may not be allowed.
The above-referenced Patent Documents and additional Patent Documents are listed below and are hereby incorporated with their English specifications and abstracts in their entireties.    1. Patent document No. 1: Japanese Patent Application Laid Open JP2011-100785    2. Patent document No. 2: Japanese Patent Application Laid Open JP2012-9760    3. Patent document No. 3: US Patent Publication No. 2013-0193458 (Your Ref. ST3001-0374)    4. Patent document No. 4: US Patent Publication No. 2013-0242100 (Your Ref. ST3001-0378)
The disclosed subject matter has been devised to consider the above and other problems, characteristics and features. Thus, embodiments of the disclosed subject matter can include providing Transistor Outlined Can-typed (To-Can-typed) semiconductor light-emitting devices including a favorable radiating structure, which can efficiently radiate heat generated from a semiconductor light source sealed in the devices, and also can enable parts of the devices not to require a high processing accuracy. In this case, the semiconductor light source can emit various colored lights in a small size. Thus, the semiconductor light-emitting devices can result in an increase in the possible range of lighting design options, and therefore can be employed for various lighting apparatuses in a comparatively small size at low cost.